1. Field of the Invention
The present invention relates to a stainless steel wire. More particularly, the present invention relates to a stainless steel wire for automatic coiling for manufacturing a spring and a method for manufacturing the same.
2. Description of the Related Art
In general, stainless steel wires for a spring have a poor heat conduction and tend to undergo remarkable workhardening. Thus, these stainless steel wires do not exhibit sufficient surface lubricant property with tools. Accordingly, these stainless steel wires are inferior to carbon steel wires for spring in drawability at the wire manufacturing and workability at the subsequent step (e.g., coiling). In other words, these stainless steel wires are disadvantageous in that they can hardly be provided with sufficient surface lubricant property at wire drawing step and subsequent steps such as coiling step, thereby making it impossible to raise the production speed sufficiently or resulting in the production of spring products having unsettled shapes. Thus, as stainless steel wires for automatic coiling there have heretofore been used those obtained by a method which comprises plating the surface of stainless steel wires with nickel (Ni), and then drawing the wire to provide better surface lubricant property at wire drawing step and subsequent steps (Examined Japanese Patent Publication No. Sho. 44-14572).
Needless to say, these stainless steel wires are superior to stainless steel wires merely coated with a resin or the like. However, these stainless steel wires cannot necessarily meet sufficiently the recent growing demand for high performance stainless steel wires free from the foregoing disadvantages.
Further, a stainless steel wire has been recently disclosed obtained by plating a stainless steel wire with nickel (Ni) to a thickness of from not less than 1 .mu.m to 5 .mu.m, coating the stainless steel wire with a synthetic resin, and then drawing the stainless steel wire to a reduction of area of not less than 60% (Unexamined Japanese Patent Publication (kokai) No. Hei. 6-226330).
The stainless steel wire disclosed in Unexamined Japanese Patent Publication No. 6-226330 can be coiled at a high rate when worked into a spring. The products thus obtained have a uniform dimension. That is, the stainless steel wire exhibits a good coilability. However, the foregoing stainless steel wire cannot necessarily meet sufficiently the demand for precision coiling at an even higher rate free from the foregoing difficulties.
On the other hand, as the solvent for dissolving a resin containing fluorine (F) or chlorine (Cl) therein there is used freon, trichloroethylene, or the like. However, these solvents are considered to be a nuisance that causes environmental destruction. Further, the foregoing resin is disadvantageous in that the low temperature annealing (tempering) after working into spring, which is an essential process for the production of spring, causes fluorine (F) or chlorine (Cl) constituting the resin to evaporate and hurt the human body.